High stakes involved in Trump's revelations to Russia

Intelligence ties and lives could be threatened, experts say.

The release of classified intelligence could have very real and dangerous repercussions on national security and the global fight against terrorism, experts tell ABC News.

The concern over protecting classified information and intelligence sources abroad comes after it was reported that President Donald Trump may have shared classified information with Russian officials when he met with them last week in the Oval Office. Trump and his associates have said that any disclosures made were appropriate in the context of the conversation and justified and under his authority.

National security adviser H.R. McMaster today said that the premise of The Washington Post report that initially revealed the disclosure was “false” but did not deny that the president shared intelligence with the Russians, adding that Trump did not reveal any sources or methods used to gather intelligence.

McMaster explained that Trump didn’t even know where the information that he shared with Russian officials had come from, but experts say that the content of the information could help reveal its source.

Danny Yatom, the former director of Israel's spy agency Mossad, warns that even if Trump didn't reveal the source -- which McMaster said the president didn't know at the time of the conversation with the Russian officials -- or methods of how the U.S. obtained the intelligence, it could still put the source in danger.

"Sometimes damage is caused from the content of the revelation, even if he does not say the methods and sources,” Yatom told The Jerusalem Post.

“The fact that you have very high-quality sensitive intelligence can lead to revealing the source. Very few people in ISIS may know about this information. Once it is publicized, ISIS can do an investigation and find the source," Yatom added.

John Cohen, an ABC News contributor and a former counterterrorism and intelligence official at the Department of Homeland Security, said that such revelations could have consequences down the road in cut ties from intelligence sources.

“It creates the risk that the original provider of the information will be less inclined to share sensitive intelligence in the future,” he said.

Before it was revealed that Israel was the source of the intelligence that was shared by Trump, Yatom described how they would have been operating from an understanding that such information would not be shared with others.

“If someone gives the U.S. very sensitive information… it is prohibited to give the information to a third party -- for sure not to Russia who has ties with Iran and Syria,” he told The Jerusalem Post.

Cohen said lives could be in danger as a result of the disclosure.

"This type of intelligence comes from very sensitive collection capabilities; it could be somebody undercover, it could be that an intelligence service has been able to bug a laptop or a cellphone… [and the disclosure] could result in someone getting killed. It could result in terrorists changing the way they communicate."

Cohen cites the intelligence dump by former NSA contractor Edward Snowden as an example of an intel setback. "Terrorist leaders changed the way they communicated because they had insight into the way we collected intelligence," he explained.

Cohen said if the report about Trump’s disclosure is true, “This is an extraordinarily serious issue and it should be taken very seriously by all Americans because it potentially could lead to our lessening of our ability to obtain vital information and that could increase the risk to the safety of Americans."